RESUMEN
Objective To assess the retention of 241Am in the whole-body bone of worker by measuring the retention of 241Am in the skull. Methods A whole-body counter with high-purity germanium detector was used to measure the 59.5 keV full-energy peak count of 241Am in the skull. The efficiency of the measurement was calibrated by the digital skull phantom combined with the geometric model of the detector. The retention of 241Am in the worker’s skull was calculated. Results The proportion of skull dry weight relative to the whole-body bone dry weight was used as the coefficient to calculate the 241Am deposition in the whole-body bone from the measured activity of skull 241Am. Conclusion With the retention of 241Am in the skull and the proportion of skull dry weight, the retention of 241Am in the whole-body bone of the worker was calculated to be about 806 Bq.
RESUMEN
Objective To develop a simplified phantom for the calibration of whole-body counters. Methods A simplified phantom design method for the calibration of whole-body counters was established based on the process and method of calibrating whole-body counters. By using the established method and Monte Carlo method, a simplified phantom including the total body, thyroid, lungs, and gastrointestinal tract was designed to calibrate the ORTEC-Stand FAST II whole-body counter. The simplified phantom was compared with the BOMAB phantom through experimental measurements. Results Within the range of 50 keV to 2 MeV, for rays of the same energy in the same organ of the simplified phantom and BOMAB phantom, the simulated data of detection efficiency by whole-body counting showed an error within 5%, and the experimental measurements showed an error within 10%. Conclusion We developed a simplified phantom for the calibration of the whole-body counter, demonstrating the feasibility of using the simplified phantom instead of a physical body phantom for whole-body counter calibration, which can greatly facilitate whole-body counter calibration for internal radiation monitoring.
RESUMEN
ObjectiveTo tentatively understand the status of radioactive contamination in nuclear medicine personnel. MethodsA total of 34 radiation staff engaged in nuclear medicine diagnosis and treatment were selected from two hospitals in Shanghai as the survey subjects.Among the 34 medical staff， 8 were nuclear medicine doctors， 14 were nuclear medicine technicians and 12 were nuclear medicine nurses. After surface contamination monitoring was first carried out to confirm that they had no surface radioactivity contamination， whole body scanning was performed with a whole body counter to determine whether they were internally contaminated with artificial radionuclides. ResultsThe α surface contamination was not detected in the nuclear medical staff. The β surface contamination of the nuclear medicine doctors， technicians and nurses was （13.8±0.8）， （14.1±0.8） and （14.0±0.7） times per second， respectively. There were 2， 2， and 4 nuclear medicine doctors who were contaminated with 18F， 99mTc and 131I， 3， 5， and 2 nuclear medicine technicians who were contaminated with 18F， 99mTc and 131I， and 6， 8， and 5 nuclear medicine nurses who were contaminated with 18F， 99mTc and 131I， respectively. The 18F activity of nuclear medicine technicians was 1 997‒9 401 Bq， and the 99mTc activity of nuclear medicine technicians and nurses was 3 699‒18 692 and 652‒388 22 Bq， respectively. One nuclear medicine nurse had a 99mTc activity of 35 389 Bq. According to the preliminary estimation of 131I internal irradiation dose， the maximum committed effective dose of nuclear medicine doctors， technicians and nurses could reach 0.370， 0.018 and 0.584 mSv， respectively. ConclusionThe nuclear medicine staff are exposed to radioactive contamination， and it is important to monitor and evaluate their internal radiation doses.